A dubious achievement for humanity

Earlier this year, scientists at the NOAA Mauna Loa Observatory in Hawaii announced a major threshold in the Earth system had been crossed: the concentration of the greenhouse gas carbon dioxide in Earth’s atmosphere has now passed a level not seen in the last 3 million years.

While CO2 concentrations vary due to natural causes, scientists are in agreement that this increase is mostly due to combustion of fossil fuels, with contributions from deforestation and other sources.

A panel of 384 leading climate scientists from 52 countries just released “State of the Climate in 2012”, an annual report compiled by the U.S. National Oceanic and Atmospheric Administration (NOAA). The scientists who prepare this report are the most experienced and qualified to evaluate changes in Earth’s climate and the effects they are having now on our planet’s ecosystems and people.

The rate of global temperature increase has slowed in the last 15 years, but 2012 still was the warmest year on record in the U.S., leading to devastating droughts in the central U.S. Additionally, 2012 was also the second-warmest on record in Mexico, the fifth-warmest in Canada, and eighth- to ninth-globally-warmest year on record since 1850 depending on which data are used.

The temperature of the world ocean was the 11th-highest on record, and the heat content in the upper ocean remains at record levels. Heat transport from the surface to the deep oceans is a major and well-documented cause of the observed slowdown in the rise of global temperatures. Sea levels are highest since accurate records have been kept. Concentrations of methane and other greenhouse gases are at or near record levels.

All these data send a clear message: Our business as usual is altering Earth’s climate system to an extent not seen for millions of years. Ecosystems and civilization will pay a heavy price for inaction. In fact, we are already paying. Ask farmers in Texas, Oklahoma and New Mexico who are abandoning family farms due to failing rains. Ask coastal residents in New Jersey battered by the worst storms on record, fueled by warming oceans. Ask fire managers in California, Idaho and Colorado battling extreme wildfires and grappling with fire seasons up to two months longer than just a few decades ago.

While the U.S. and other nations delay addressing the problem and uninformed bloggers muddy the issue, the scientific community is unified in its understanding of the challenge of global climate change. The American Geophysical Union, the largest and most distinguished professional organization of Earth and physical scientists, has released a statement titled “Human-Induced Climate Change Requires Urgent Action.”

Every other major organization of qualified atmospheric and Earth system scientists has come to similar conclusions. In fact, a recent study of nearly 12,000 published papers authored by almost 30,000 climate scientists around the world concluded that “the number of papers rejecting the consensus on AGW (anthropogenic global warming) is a vanishingly small proportion of the published research.”

The scientific debate is over; what remains are the politics.

While scientists may (and often do) disagree on fine points of a particular data set or analysis, there is no serious dissent about the big picture: Earth’s climate is changing at rates that have not been experienced for millions of years, and the primary driver of these changes is human action.

The consequences of inaction are costing society more in drought and disaster relief, the spread of diseases and giant wildfires. Acting now allows us to take advantage of opportunities to improve efficiencies in water use, electricity generation and distribution, and public transportation to reduce our carbon emissions into the atmosphere. We can also develop or repair needed infrastructure (reservoirs, coastal wetlands, high-speed intercity rail), and improve the health of our forests and watersheds.

Climate change is inevitable and already happening, but how much worse it gets is up to us. Time is running out fast.

Donald A. Falk is an associate professor in the University of Arizona’s School of Natural Resources and the Environment. Email him at dafalk@email.arizona.edu

Gregg M. Garfin is deputy director for Science Translation & Outreach, Institute of the Environment at the UA. Email him at gmgarfin@email.arizona.edu